The present invention relates to a printing press with a plate making unit for performing plate making for a plate mounted on the plate cylinder of a printing unit.
Generally, when performing plate making for a plate, it is required to increase the efficiency of plate making operation and to eliminate the space where a plate making unit is to be installed. Hence, in recent years, a plate making unit independent of the printing press is not provided, but a plate making unit added to the printing press itself performs plate making directly on the printing press. More specifically, a plate before plate making is mounted on a plate cylinder in a printing unit, and the plate making unit is moved to abut its head against the plate cylinder. Subsequently, the plate cylinder is rotated, and simultaneously the head is moved in the axial direction of the plate cylinder, thereby performing plate making for the plate. When the plate is to be supplied/removed or maintenance is to be performed, the plate making unit is separated from the printing unit, and the head is removed from a support member.
When performing plate making operation, the head must be attached to the support member again, and the position of the head with respect to the plate cylinder is not always the same as the position where the head has been removed from the support member. Therefore, since the distance between the head and plate cylinder is not made equal to a predetermined distance when the plate making unit comes close to the plate cylinder, the position of the head with respect to the plate cylinder varies, thereby degrading plate making precision and causing defective plate making.
It is an object of the present invention to provide a printing press which prevents defective plate making by improving plate making precision.
In order to achieve the above object, according to the present invention, there is provided a printing press comprising a plate cylinder which is rotatably supported by a frame and has an outer surface on which a plate is mounted, a plate making unit for performing plate making for the plate mounted on the plate cylinder, the plate making unit having a support member supported by the frame and an exposure unit supported by the support member to be movable in a direction to come close to and separate from the outer surface of the plate cylinder, the exposure unit being provided with a head which irradiates the plate with a laser beam to print an image on the plate, and an adjuster supported by the plate making unit to be detachable to adjust a position of the exposure unit with respect to the support member.